package com.arron.algorithm.huawei;

import java.util.Scanner;

//华为机试 HJ107 求解立方根
public class Cube {


    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);

        double v = sc.nextDouble();

        double left = Math.min(-1,v);
        double right = Math.max(1,v);
        double i = 0;
        while (Math.abs(right-left)>0.01){

            i = (right+left)/2;
            if ( i*i*i > v){
                right = i;
            }else {
                left = i;
            }

        }
        System.out.println(String.format("%.1f", i));

    }


}
